46 THE ESSEX NATURALIST
We may therefore assume with reasonable certainty that the Saxon surveyor
would be aware of certain celestial facts. He would know, for example, that
at the time of the Equinox the shadow of an object travels during the day in
a straight line due west and east. Without a doubt he would also know how
to determine the North and South from observation of the Pole Star.
Upon these basic assumptions we may now reconstruct the probable pro-
cedure of the Saxon surveyor, planning his new church entirely from observa-
tions of the Sun's motions.
Let us go back in imagination to the 7th century, and to the site, say, of
Chickney church. It is the morning of the Spring Equinox, March the 20th.
The villagers are in festive mood, preparing for the pagan feast to herald the
return of summer. Our Saxon builder has set up a pole on the rising ground,
and hour by hour he marks the passage of the shadow of its top as it moves
in a straight line from west to east. That night, as the festive fires burned in
the village, he took a bearing from the pole-top to the North Star, and
marked the direction along the ground with a second row of sticks or
stones.
Having thus determined the cardinal points of direction upon his site, there
came a long pause in his procedure, until the day of the Summer Solstice,
June the 24th. Again the preparations are being made, on this occasion for
the festivities of Midsummer Day. The builder has chosen a pole, equal in
length to the intended width of his church. He sets it up vertically on the
intersection of his two lines of markers, the one lying due east and west, and
the other north and south. The summer sun casts a shadow of the pole,
which, as the day passes, moves through an arc so that the top of the pole
makes a hyperbola of which the most northerly point is at midday. Then, as
the Sun sinks towards the west, the shadow reaches out eastwards and at
4.46 p.m. just lies along the E-W line. At this moment he places a stone at
the very place where the top of the pole's shadow touches. This is the easterly
point of his church. Then he throws down the pole so that it lies along the
N-S line. This gives him his width. Finally, as accurately as he can, he
completes the plan by marking out the remaining two sides, but here, having
no celestial guide to help him, the angles are irregular and the sides not
parallel. Only the south-west corner is a right-angle; the others are struck
more by luck than good judgment. The north and south walls splay out a
little, and the north-east corner is noticeably acute.
You may see these things for yourself at the ancient church of Chickney
today.
This reasoning not only explains the irregularity of the corners of Saxon
naves, but it also gives a meaning to the observed Length to Width proportion
of root-three to one; for it can be shown both experimentally and by mathema-
tical calculation than on Midsummer Day, i.e., the Solstice, the shadow of an
object falling due east or west of it subtends an angle of about 30 degrees, for
the latitude of Essex, and the cotangent of this angle is √3.
In the summer of 1956 I set up a simple apparatus, consisting of a stick,
ten inches long, standing vertically upon a flat board. The latter was aligned
with its edge due east and west, and observations taken in sunshine on the
24th of June. On that day the period of sunshine was intermittent, but
fortunately covered the time when the shadow fell along the eastern line, at
4.46 p.m. Direct measurement proved that the length of the shadow, 16|
inches, bore out the required relationship.
Mathematical treatment involves three-dimensional data and the
laws of trigonometry. It is sufficient here to state that the length of